Thomas Aquinas

“ I answer that, If a man has connection with the sister or other relative of his wife before contracting marriage, even after his betrothal, the marriage should be broken off on account of the resultant affinity. If, however, the connection take place after the marriage has been contracted and consummated, the marriage must not be altogether dissolved: but the husband loses his right to marital intercourse, nor can he demand it without sin. ”

“ Now for the most part this age is the fourteenth year in males and the twelfth year in women: but since the ordinances of positive law are consequent upon what happens in the majority of cases, if anyone reach the required perfection before the aforesaid age, so that nature and reason are sufficiently developed to supply the lack of age, the marriage is not annulled. Wherefore if the parties who marry before the age of puberty have marital intercourse before the aforesaid age, their marriage is none the less perpetually indissoluble. ”

“ Now through the action of man, a person may be rendered incapable of carnal copulation by some power or by castration; and this is an impediment to marriage. Therefore much more can this be done by the power of a demon.
I answer that, Some have asserted that witchcraft is nothing in the world but an imagining of men who ascribed to spells those natural effects the causes of which are hidden. But this is contrary to the authority of holy men who state that the demons have power over men's bodies and imaginations, when God allows them: wherefore by their means wizards can work certain signs. ”

“ I answer that, In marriage there is a contract whereby one is bound to pay the other the marital debt: wherefore just as in other contracts, the bond is unfitting if a person bind himself to what he cannot give or do, so the marriage contract is unfitting, if it be made by one who cannot pay the marital debt. This impediment is called by the general name of impotence as regards coition, and can arise either from an intrinsic and natural cause, or from an extrinsic and accidental cause, for instance spell, of which we shall speak later [4984] (A [2] ) . ”

“ But a spell cannot be a perpetual impediment, for since the devil has no power over others than sinners, the spell will be removed if the sin be cast out, or by another spell, or by the exorcisms of the Church which are employed for the repression of the demon's power. Therefore a spell cannot be an impediment to marriage.
Objection 4: Further, carnal copulation cannot be hindered, unless there be an impediment to the generative power which is its principle. But the generative power of one man is equally related to all women. ”

“ In matters to which nature inclines there is not required such a development of reason in order to deliberate, as in other matters: and therefore it is possible after deliberation to consent to marriage before one is able to manage one's own affairs in other matters without a guardian. ”

“ Although the act of carnal copulation is not essential to marriage, ability to fulfill the act is essential, because marriage gives each of the married parties power over the other's body in relation to marital intercourse. ”

“ Some spells are so perpetual that they can have no human remedy, although God might afford a remedy by coercing the demon, or the demon by desisting. For, as wizards themselves admit, it does not always follow that what was done by one kind of witchcraft can be destroyed by another kind, and even though it were possible to use witchcraft as a remedy, it would nevertheless be reckoned to be perpetual, since nowise ought one to invoke the demon's help by witchcraft. ”

“ Further, generally speaking woman is more frigid than man. But women are not debarred from marriage. Neither therefore should men be debarred on account of frigidity.
On the contrary, It is stated (Extra, De Frigidis et Malefic., cap. Quod Sedem) : "Just as a boy who is incapable of marital intercourse is unfit to marry, so also those who are impotent are deemed most unfit for the marriage contract." Now persons affected with frigidity are the like. Therefore, etc.
Further, no one can bind himself to the impossible. Now in marriage man binds himself to carnal copulation ”

“ Now this opinion grows from the root of unbelief or incredulity, because they do not believe that demons exist save only in the imagination of the common people, who ascribe to the demon the terrors which a man conjures from his thoughts, and because, owing to a vivid imagination, certain shapes such as he has in his thoughts become apparent to the senses, and then he believes that he sees the demons. ”

“ The first corruption of sin whereby man became the slave of the devil was transmitted to us by the act of the generative power, and for this reason God allows the devil to exercise his power of witchcraft in this act more than in others. Even so the power of witchcraft is made manifest in serpents more than in other animals according to Gn. ”

“ But such assertions are rejected by the true faith whereby we believe that angels fell from heaven, and that the demons exist, and that by reason of their subtle nature they are able to do many things which we cannot ”